Code stopped working without being changed - Stack Overflow thinks it's a github issue.

[233116]

Select Topic Area

Question

Body

Hi all, I have been working on a project for my computer science college coursework and have recently come across an issue where sections of my code have stopped working even though I haven't changed any of the code in them. I asked on Stack Overflow what could've caused this, as there are no error messages, just non-functioning code. The majority of answers on there told me that it sounds like a github issue, and I was wondering if anyone here has encountered a similar issue/knows anything about how to fix this or what caused it? I've tried reverting back to previous versions of my GitHub repository but it errors with a "fatal error". I've also re-written everything within the code that's stopped working and still nothing. It was working a few days ago and all I've changed since then is re-writing the code that's stopped.

[dreamypro]

I ran into something similar before, and when code suddenly stops working without any changes, it’s usually not the code itself, it’s something around it that changed.

The first thing I’d check is dependencies. If you’ve run something like npm install or pip install, newer versions might have been pulled in (especially if versions aren’t locked). That alone can break things. I’d try reinstalling clean or restoring a previous lock file:

rm -rf node_modules package-lock.json
npm install

Next, I’d look at the environment. Even a small change like a Node/Python version update or missing environment variable can cause issues. It’s worth checking your versions (node -v, etc.) and making sure your .env file hasn’t changed or gone missing.

Another thing to consider is config files. Files like .env, .npmrc, or build configs can affect behavior more than expected.

Lastly, it could just be caching. Clearing cache and deleting build folders (dist/, build/, .next/) has fixed this kind of issue for me before.

---

If reverting to an older commit still doesn’t fix it, I’d be pretty confident it’s something environment or dependency-related rather than your code.

[ajx-dev]

This honestly doesn’t sound like a GitHub issue.

If your code stopped working “without changes”, it’s almost always something around the code, not GitHub itself.

A few things I’d check:

• Dependencies: did anything update automatically? (packages, libraries, etc.)
• Environment: different Node/Python version? OS changes?
• Config or env files: .env, paths, API keys, ports…
• Caching: sometimes things break because of old cache (try reinstalling dependencies or clearing cache)
• That “fatal error” when reverting might point to a local repo issue rather than your code itself

Also, rewriting the same code won’t fix it if the root cause is external.

GitHub just stores your code, it doesn’t execute it, so it usually isn’t the source of this kind of problem.

If you can share the actual error (especially the “fatal error”), that would help narrow it down

[alex-gamero]

Personally I think the issue is almost certainly not GitHub.
Here's a way you can find the real cause:

GitHub is just a storage system for your code, it doesn't run anything, so it can't be responsible for runtime behaviour changes. The "fatal error" you're seeing when reverting is likely a merge conflict or a dirty working tree
run git status first, and make sure your working directory is clean before reverting.

That said, here's how I'd approach this:

1. Isolate when it broke
   Usegit bisect to find the exact commit where things stopped working:

git bisect start
git bisect bad          # current broken state
git bisect good <hash>  # a commit you know worked

Git will walk you through commits until it pinpoints the change. Even if you didn't touch that code, something changed somewhere.

2. Check for silent dependency updates
   If your package-lock.json or requirements.txt isn't committed, dependencies may have auto-updated. Compare what you have now vs. what was there when it worked, even a minor version bump can break things.

3. Reproduce in isolation
   Copy just the broken section into a minimal standalone file and test it alone. This rules out interference from other parts of the project (imports, global state, etc.).

4. Fix the "fatal error" when reverting
   That error usually means one of:

• Uncommitted changes blocking the revert → git stash first
• A corrupted local repo → try cloning a fresh copy from GitHub
• You're reverting a merge commit → use git revert -m 1 <hash>

The fact that rewriting the same code also doesn't fix it is the strongest clue.
Probably that means the bug is almost definitely environmental or dependency-related, not in your logic. git bisect is your best friend for tracking down exactly what changed.

[Medeiroshenrique]

It can happen because of your IDE, because of your local machine(you maybe updated something unexpected - I don't hope so nor think so) or you just need to reboot your machine(computers are completely unpredictable sometimes, trust me) .

[frazrajpoot01]

Hi there. Just to clear up what the Stack Overflow folks might have meant: GitHub itself cannot break your local code. It just stores your files. If code stops working without you changing it, the issue is almost always in your local environment.

The "fatal error" you're getting when trying to revert is likely because you have uncommitted changes. To safely test an older version without losing your current work:

Run git stash in your terminal to temporarily shelve your current changes.

Run git checkout (using the hash from a few days ago when you know it worked).

Test it. If the old code still doesn't work, you know 100% the code isn't the problem. When this happens, it usually comes down to:

A dependency or package that updated in the background.

An external API or database connection failing.

Corrupted browser cache/local storage (if this is a web project).

[jdld-ybd]

Most likely it's a problem with the code itself, dependencies, or the environment (if there are no error messages), because GitHub is still very stable 大概率是代码本身或依赖或环境的问题（没有错误信息的话），GitHub还是很稳定的